When a multichannel microwave communications system is used to enhance a signal-to-noise ratio of a communications link and reduce interference between different links, phase shifters on channels need to be adjusted depending on channel information between the links, so as to form an expected beam shape on an antenna array.
In the prior art, a multichannel microwave system usually uses an analog multichannel structure. When estimating channel information (or a channel matrix), such an analog multichannel system that uses the analog multichannel structure needs to estimate parameters of subchannels in the system at different times. A specific implementation method thereof is that: a radio frequency switch or a variable gain amplifier is added on each subchannel; then subchannels are controlled to be switched on/switched off by using the switches or by means of gain adjustment on the subchannels; subchannels between pairs of antennas of a transmitter and a receiver are traversed sequentially, and parameters corresponding to the subchannels are obtained separately; and finally, complete channel information is obtained by means of combination.
However, in the foregoing channel estimation method, using of a radio frequency switch increases an insertion loss of a channel and degrades link performance; and a variable gain amplifier increases nonlinearity of the channel, and a gain suppression capability of the variable gain amplifier is limited. This leads to energy leakage, thereby affecting precision of a channel estimation result. In addition, adding the radio frequency switch or the variable gain amplifier on the channel also increases a cost and a volume of the system.